Huot, Gabriel, Sumatra FWI

Huot, Gabriel

Application of full elastic waveform inversion to CGGVeritas 15 km long offset data

S. Singh (IPGP)

The aim of this thesis is to explore the deep structure under the Sumatra subduction zone. We apply elastic FWI to an ultra-long offset (15 km) deep seismic reflection dataset. The seismic pro- file CGGV20 is 270 km long acquired by CGG across the Sumatra subduction in the rupture zone of the 2007 earthquake. Unlike usual exploration data, the recording length was longer (20 s), the streamer was dived deeper (22.5 m) and the source was triggered deeper (15 m). These characteristics provide data with low frequency content, which make it suitable for FWI. To match our modelling with the observed data, we estimate the source wavelet. Then, the same pass-band filter was applied to both the source and the observed data. Additionally, an f-k filter was applied to the real data to remove the remaining swell noisewithout losing any useful signals. Despite a smooth starting model, first application provides reliable results in the shallow part, and also consistent with the PSDM features. We aim to obtain considerably better FWI results by applying a tomography to improve the starting model.